Axis converter



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ArrpR United States Patent O AXIS CONVERTER Paul M. Birk, Williamsville,N. Y., assignor, by mesue assiguments, to the United States of Americaas represeuted by the Secretary of the Army Application February 27,1953, Serial No. 339,279

15 Claims. (Cl. 33-46) The present invention relates to an axisconverter.

With the introduction of air Warfare and defense by anti-aircraft, andin view of the high speed of modem aircraft, mechanical aids for firecontrol have been supplanted by automatic means for making computationswith suflicient rapidity to satisfy the speed requirements. One suchdevice is the director which comprises means for continuously observingopti'a the elevation and azimuth of a target, and including automaticmeans utilizing electrical crcuits to make the necessary computatons andto translate them into gun'settings.

In Operating the director observatious are takeh, and from theseobservations the director makes all the necessary computations andtransmits the results in suitable form for directing the guns. Thecalculations, as indicated, are made continuously, and without delay andwith a high degree of accuracy, so that the guns may be fired aty anyinstant after computations are made and as long as the target is withinrange. The director operator optically observes at a given instant theazimuth and elevation of the target with respect to a horizontal plane.Other means such as an optical height finder, or radar are used toobtain the range or height of the target at that same instant, and themechanical movements of the director n making the necessary observationsthen are translated into electrical impulses.

Commencing with the basic assumption that the target will continue tomove in a straight line at constant speed while the projectile is inflight, the necessary calculations are made automatically andtransformed into terms of firing azimuth, quadrant elevation, and fuzesetting required to direct a gun battery so that at a predetermined timeinterval after the observations are made a fired projectile and thetarget will meet at the same point in space, whereupon the projectilewill explode to destroy the target.

In the known directors, the observed azimuth and elevation readings aretaken with respect to the ground. However in certain circumstances, whengreater accuracy in locating the future position of the target isdesirable, the conversion of the azimuth and elevation readings to aVertical plane perpendicular to the ground has been found to be of greatassistance in more accurately locating the present position of a targetmoving iu space.

In addition to providing the means for more accurately predicting thepresent position of a target moving in space the axis converter is alsoused to alter the flight course of a guided missile so that the missilemay be steered to a fixed target. In this situation the missile isprovided with a control system actuated by a signal sent from theground. In order to furnish the missile with the proper signals to alterits course, it is necessary to supply information in regard to bothpitch and yaw. ln actua'l practice, therefore, the gun director modifiedby the addition of the axis converter, gives azimuth and elevationangles both with respect to the ground, and

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with respect to a plane perpendicular to the ground. This information isthen sent to a computer which in turn feeds a transmitter, and sends asignal to the missile in flight so that the missile will follow a coursedesired by the operator of the gun director.

In addition to the four angles, it is also necessary to feed into thecomputer information as to the exact location of the target toward whichthe missile is headed.

lt is accordingly an object of this invention to provide means forconverting azimuth and elevation readings of a director to a Verticalplane perpendicular to the ground.

It is also an object of this invention to provide mechanical apparatusintegral with the structure in a director upon which the telescope ismounted, for transforming 'azimuth and elevation reading with respect tothe ground, to a vertical plane perpendicular to the ground.

It is also a further object of this invention to provide a linkagesupportable upon brackets made integral with the azimuth gear formingpart of a rotating head for a director. The linkage is responsive tomovement of the rotating head in azimuth and the observing telescope inelevation to respectively rotate an output shaft and to slide a secondshaft within the output shaft to thereby give azimuth and elevationangles relative to a Vertical plane perpendicular to the ground.

With these and other objects in view which will become apparent as thespecification develops, reference is made to the accompanying drawingforming part of the specification wherein like numerals have been usedto designate corresponding or similar parts and wherein:

Figure 1 is a view in perspective of the axis converter linkage formingpart of a rotating head of a director.

Figure 2 is a diagram illustrating the input azimuth and elevationangles with respect to a horizontal or ground plane and thecorrespouding angles as transformed 'by the converter to a vertcal planeperpendicular to the ground plane.

Referring to the drawings reference character 1 designates a portion ofthe tracking head comprising a platform or plate 2 which is rotatable inazimuth about a vertical or azimuth input" axis Y-Y with respect to theground, by -an operator. Plate 2 is peripherally notched as at 3 to forman azimuth gear for transferring azimuth positions to synchro units (notshown) which in turn transmit azimuth or gun train orders to a gun mountor computer. A pair of diametrically opposed upstanding support members4 and 5 are secured to the upper face of plate 2, and are provided withhorizontally alined holes 6 and 7 in which is journaled a shaft 8, uponwhich is integrally mounted an observing telescope 9. On the extremeends of shaft 8 are mounted gears (not shown) for drivng synchro units(not shown) which transmit elevation orders to a gun mount or computer.

The support structure for the axis converter linkage comprises a pair ofdiametrically opposed downwardly extending brackets 10 and 11 eachhaving one end securedin any convenient manuer to the lower face ofplate 2 and with the free lower ends provided with horizontally alinedholes 12 and 13 into which is journaled a transfer shaft 14. Brackets 10and 11 are in Vertical alinement with upwardly extending supports 4 and5 so that transfer shaft 14 is always normal to the input azimuth axis,and parallel to and in Vertical alinement with telescope shaft 8. It canreadily be seen therefore, that when plate 2 and shaft 8 are moved inazimuth, transfer shaft 14 also moves accordingly. Means are alsoprovided to correspondingly rotate transfer shaft 14 in elevation tofollow a like movement of telescope 9 14, land vertically alined withpinion 15. Plate 2 is provided with a central hole 17 through whichextend vertically reciprocable push-pull rods 18 and 19 havingrespectively upper and lower racks 20 and 21 each engaging pinions 15and 16 on one side, and upper and lower racks 22, 23 engaging pinions 15and 16 on diametrically opposed sides. As the telescope is moved inelevation, transfer shaft 14 rotates accordingly due to the action ofthe above described action of the push-pull rods on the racks andpinions. The axis of rotation of the transfer shaft may be designatedthe input elevation axis X-X.

The converter linkage per se comprises a pair of parallel elongated arms25, 26, each having one end mounted on transfer shaft 14, such that arms25 and 26 are always parallel to the line of sight of the telescope, andthe free ends apertured as at 27, 28 to receive a pivot pin 29, uponwhich are in turn mounted downwardly extending parallel links 30, 31having a shape somewhat as a "boomerang, and which are apertured attheir extreme ends as at 32, 33. Received in these latter holes arepivot pins 34, 35 extending outwardly from opposed sides of ahexahedronal block or gimbal 36. provided with an axial bore 37, normalto the axis of pins 34, 35, for receiving with a smooth fit a stud orpin 38 forming an elongaton of the larger leg 39a of a bell crank member39. By this construction, the arm 39a of bell crank 39 may pivot inblock 36 about the axis of its reduced end or pin 38, and may pivotabout the axis of pins 34 and 35 in a plane midway between the links and31. The extreme ends of pins 34, are threaded to receive nuts 40(oneshown) to maintain gmbal 36 secure between links 30, 31. The freeend of pin 38 is also threaded to receive a nut 41, such that when thelinkage is assembled, little or no clearance is provided betweenabutting faces of gimbal 36 and bell crank member 39.

The axis converter also includes a cradle structure 24 for mountingelements which cooperate with the above described linkage to define the"output" axes, or the axes which correspond to the azimuth and elevationmeasurements relatve to a Vertical plane perpendicular to the ground.This structure comprises horizontally spaced Vertical end plates orsupport brackets 42, 43 secured to a base plate (not shown). The baseplate in turn is Secured to the base (not shown) of the director, whichis non-rotating. The end plates 42, 43 are provided with horizontallyalined holes 44, in which are journaled stud shafts 44a and 45a forminga second transfer shaft which defines an axis of rotation for cradle 24which may be termed the output azimuth" axis Y'--Y'. A built up metalplate construction 47 forming part of cradle 24 comprises an upwardlyopening box structure extending from end plate 42 for approximatelytwo-thirds the distance to end plate 43, and includes a channel member48 having turned up sides 49 and a left end 50 also turned up so as tohave a depth equal to approximately twice the depth of sides 49,adjacent bracket support or end plate 42. The opposed end of box 47 iscovered by-a plate 51 to complete the box, and a U-shaped strap orsupport member 52 is Secured in any convenient manner to the outsidesurfaces of turned up sides 49 and 50. To the outer surface of box end50 and above strap 52 is secured a support plate or bearing plate 53 toabut the inner surface of end plate 42, and to this plate is aflixedstud shaft 44a to extend through hole 44 in plate 42. The free end ofshaft 44a is threaded at 46 to receive a nut 54 to retain the associatedparts together.

Adjacent end plate 51. sides 49 of box 47 are provided with upwardlystruck parallel brackets 55 and 56 integral therewith, and extendingupwardly to the same height as box end plate 50. Secured to the innerfaces of brackets 55, 56 are parallel elongated horizontal bars 57, 58having their extreme ends abutting the inner surface of end plate 43,and having Secured between the abutting ends a hexahedronal plug 59provided with a horizontal bore 59a in alinement with hole 45 in plate43. A hollow sleeve member forming stud shaft 45a is secured to theabutting face of plug 59 with its aflixed end surrounding bore 59a andwith its other end extending loosely through hole 45. A gear 60 ismounted on shaft 45a adjacent the outer face of end plate 43 and a nut61 screwed on shaft 45a holds together shaft 45a, gear 60 and plug 59with bars 57, 58. These elements and box 47 taken together form thecradle 24 untarily rotatable about axis Y'-Y'.

The above described converter linkage provides the impetus for rotatingthe cradle about axis Y'- with the connection between the two structurescomprising a pin 62 extending through alined holes 63 and 64 and 64aformed respectively in the apex of bell crank member 39 and inhorizontal bars 57, 58, the shorter leg 39h of the bell crank extendingupwardly and to the right as seen in Figure 1, and the apex fittingsnugly between bars 57 and 58. The upper end of leg 39b is bi-furcatedas at 65 and each leg of the bi-furcation is provided with alined holes66 (one shown) to receive a pin 68 upon which is mounted a roller 70,which in turn is adapted to bear against the flat abutting face of aslide member 71 adapted for reciprocable translation between bars 57 and58, and guided for such translation by a cylindrical slide rod 72secured to the face opposed to the roller abutting face thereof, andextending for reciprocation through hollow sleeve 45a. Slide 71 is alsoprovided with a portion 73 extending below the surfaces of bars 57, 58,and extending horizontally therefrom in a direction opposed to slide rod72 is a second slide rod 74 reciprocable through a hole 75 in plate 51and extending into box 47. A compression spring 76 surrounds slide rod72 and extends between slide 71 and plug 59 to bias slide 71 to the leftas seen in Figure 1 and into contnued abutting engagement with roller70.

In describing the operation of the axis converter brief reference willbe made to elements of the director apparatus which are not important tothe invention on hand and have not been illustrated. Referring to Figure1, the usual director includes handles (not shown) attached to the endsof shaft 8, readily accessible to an operator for turning the telescope9 in elevation about an axis through telescope shaft 8. The director isalso equipped with a strap (not shown) connected to the rotating headand adapted to fit about the waist of the operator so that the pressureof his body assists the pressure upon the telescope handles to move thedirector head in train. As the telescope is moved in elevation, andtrain, gearing connected to shaft 8, and to azirnuth gear 3 drivesynchro units or telemetric transmitters for transmitting elevation andazimuth orders to a gun mount computer. As previously indicated theseorders are related to a horizontal plane, or to the ground, and it isthe purpose of the present invention to convert the elevation andazimuth readings to orders taken relative to a Vertical planeperpendicular to the ground.

As the telescope is rotated in elevation, this rotation is transmittedto input elevation axis X-X by virtue of the motion imparted topush-pull rods 18 and 19, and the action of pinions 15, 16 and racks 20,21, 22 and 23. Arms 25 and 26 are accordingly rotated about this axis ino either clockwise or counterclockwise direction as the case may be, inparallelism with the line of sight of telescope 9, and this rotation isin turn transmitted to converter links 30 and 31 through pivot pin 27,imparting either thrust or a pull combined ordinarily with a rotation ofblock 36 about pin 38 to the connection with bell crank member 39. As aresult of the swivel connection between gimbal 36 and bell crank member39, and since bell crank member 39 is constrained against lateralmovement because of pivot pin connection 62 with bars 57, 58, bell crank39 will pivot either in a clockwise or counterclockwise direction tocause roller to traverse the flat abutputer.

ting face of slide member 71, wherefore slide member 71 and rod 72 arecaused to reciprocate either to the right or left assisted by thecompressive action of spring 76. Since slide rod 74 is integral withslide member 71, it also reciprocates within hole 75 in plate 51. Theaxial translation of rod 74 may be taken off by suitable rack and gearmechanism (not shown) to drive telemetric transmitter means to conveysuch motion to a computer. The arrangement of the linkage is such thatthe longer leg 39a of the bell crank 39 defines the elevation angle withrespect to a Vertical plane, and the lateral movement of the slidedefines a position or produces a signal which is proportional to thecosine of the elevation angle with respect to that Vertical plane. Thislatter angle transmitted to the computer is sutficient for the desiredpurpose, as it may be there reconverted by mechanism similar to thatshown to angular values.

The director head when turned in azimuth rotates about axis Y-Y, or theinput azimuth axis of the director azimuth gear, as previouslyindicated, and is connected with a train of gears (not shown) fordriving other synchro units (not shown) for transmitting azimuth orderswith respect to the ground, to the gun mount or com- As the azimuth gearrotates, brackets and 11, which are integral therewith, also rotateabout this axis to rotate the entire converter linkage to cause bellcrank member 39 to rotate the entire cradle structure including gear 60,mounted in shafts 44a and 45a about azimuth output axis Y'-Y', andthrough gear 60, this movement in turn drives synchro units (not shown)to transmit azimuth orders relative to a Vertical plane perpendicular tothe ground, to a gun mount or computer. In other words, the motion ofgear 60 produces a signal which is proportional to BAX as shown in Fig.2. Still referring to Fig. 2 it will be seen that sinPAC(PA) 1) ;sam-mBAX since Q 1 A eos PAC Equation 1 becomes sin PAC (2) cosPAC cosCAXtanBAX since sin PAC aFA-Crt'fl O Equation 2 becomes tan PAC (3) m-tnBAX Therefore, the rotation and pivoting of the telescope, azimuth andelevation movements respectively, operating on the axis converterlinkage above described, produces a signal through movement of gear 60which is proportional to the angle whose tangent is equal to the tangentof the angle of rotation, or azimuth, multiplied by the recprocal of thecosine of the pivotal angle, or elevation.

In explaining the operation of the converter, it is to be noted that nomention has been made of any effect on the movement of the outputazimuth axis when the telescope is moved in elevation. Likewise inmoving the director head in azimuth only the corrcsponding effect on theoutput azimuth" axis has been described. It is apparent that in view ofthe gimbal connection of the converter links to the bell crank member,and because of the rcstraint provided by the pivotal connection of thebell crank member with the cradle structure mounted on axis Y'-Y', amovement in elevation of the telescope will, in the normal operation ofthe directors, have some effect on the output azimuth" axis also, and inlike manner rotation of the director head in azimuth will also infiu---6 ence the output elevation axis. Figure 2 delineates graphically theelevation and azimuth angles of a line of sight with respect to theground and Vertical planes. Reference to this figure will serve toillustrate the effect of a change in the line of sight on the variousangles shown. For example, AP is the line of sight, XAC denotes azimuthwith respect to the ground plane and PAC represents the elevation withrespect to the ground. PAB is the elevation as to a Vertical planeperpendicular to the ground, whereas BAX represents azimuth as to thisvertical plane. g

When the telescope is moved in elevation only, PAC will change and XACremains the same. The axis converter linkage will cause a change in bothPAB and BAX. So also when the telescope is moved in train CAX willchange and PAC will remain the same, however both angles PAB and BAXwill change. In other words, if the telescope is elevated withoutchanging its direction in azimuth, the converter linkage will pivot thebell crank member to effect a corresponding change in the elevation ofthe line of sight with respect to the Vertical plane. Simultaneously theaction of the linkage will be transmitted to the bell crank member 39through gimbal 36 to rotate cradle structure 24 about axis Y'- to effecta small change in output azimuth In like manner, a change in train onlyof the telescope also effects a change in output elevation" as well asthe more noticeable change in output azimuth."

There are however special exceptions to the above described movements inboth output elevation and azimuth output" for changes in direction ofthe telescope. The first exception is when the line of sight is at zeroelevation, and PAC is zero. For this position of the telescope, thecradle structure is turned through an angle such that any change ininput azimut will effect a corresponding change in output elevationonly. This is clearly seen by referring to Figure 2, since for thiscondition points (P) and (C) are co-incident and (B) now lies in theline of intersection of the ground and Vertical planes, therefore achange in CAX atfects only PAB. The second exception obtains when theinput azimuth angle is zero. In this position of the telescope, (P) and(B) are co-incident in the Vertical plane and (C) lies in r theintersection of the two planes between (X) and (A).

Hence any change in elevation of the line of sight to change inputelevatioz PAC will affect a corresponding change in output azimuth" BAConly. In the linkage llustrated in Figure l, when the telescope is setat zero azimuth, leg 39b of bell crank member 39 lies in the axis Y'-Y'.I-Ience any change in elevation of the telescope will have notranslatory effect on slide member 72. However the linkage will serve torotate the cradle about axis Y'- to correspondingly change the outputazrnut angle.

The above described axis converter linkage is illustrative ofapplicant's apparatus to convert line of sight readings with respect toa ground plane, to a Vertical plane perpendicular to the ground. Howeverthe disclosed de- Vice is merely exemplary, and numerous othermodifications and alterations of the same will be apparent to oneskilled in the art. It is obvious that any such modification may be madewithout departing from the spirit and scope of the invention as definedin the following claims.

I claim:

l. An axis converter mounting a telescope rotatable in a first fixedplane and pivotable about an axis parallel to said first fixed plane andin a series of intersecting planes normal to said first fixed plane, andmeans responsive to the movement of said telescope to produce a signalproportional to the angle whose tangent is equal to the tangent of theangle of rotation multiplied by the recprocal of the cosine of the pivotangle.

2. The converter in claim l wherein said means comprises linkageunitarily rotatable with said telescope about a common axis, and meansconnected to said telescope i l t i t l zarania? pivoting means forpivoting said linkage about an axis parallel to and in Verticalalinement with the pivotal axis of said telescope.

3. The converter in claim 2 including a cradle structure having a swivelconnection with said linkage and rotatable in response to movement ofsaid telescope and said linkage, about an axis parallel to said firstfixed plane and defining output azimuth with respect to said Verticalplane, and a slide connected to said linkage and horizontallyreciprocable within said cradle in response to pivoting of saidtelescope to define output elevation with respect to said Verticalplane.

4. An axis converter comprising a head rotatable in azimuth and mountinga telescope pivotable in elevation, said azimuth and said elevationbeing with respect to a ground plane, and means responsive to themovement of said head in azimuth and said telescop' in elevation toproduce a signal proportional to the angle whose tangent equals 5. Theconverter in claim 4 wherein said means comprises linkage unitarilyrotatable with said telescope about a common axis, and means connectedto said telescope pivoting means for pivoting said linkage about an axisparallel to and in Vertical alinement with the pivotal axis of saidtelescope.

6. The converter in claim 5 including a cradle structure having a swivelconnection with said linkage and rotatable in response to movement ofsaid telescope and said linkage, about an axis parallel to said groundplane and defining output azimuth with respect to said Vertical plane,and a slide connected to said linkage and horizontally reciprocablewithin said cradle in response to pivoting of said telescope to defineoutput elevation with respect to said Vertical plane.

7. An axis converter mounting a telescope rotatable in a horizontalplane defining input azimuth With respect to the ground, and pivotablein a plurality of Vertical intersecting planes defining input elevationwith respect to the ground, and means responsive to said input azimuthand said input elevation to produce a signal proportional to the anglewhose tangent equals tangent of input azimuth cosine of input elevation8. The converter in claim 7 wherein said means comprises linkageunitarily rotatable with said telescope about a common axis, and meansconnected to said telescope pivoting means for pivoting said linkageabout an axis parallel to and in Vertical alinement with the pivotalaxis of said telescope.

9. The converter in claim 8 including a cradle structure' having aswivel connection with said linkage and rotatable in response tomovement of said telescope and said linkage, about a horizontal axisdefining output azimuth with respect to said Vertical plane, and a slideconnected to said linkage and horizontally reciprocable within saidcradle in response to pivoting of said telescope to define outputelevation with respect to said Vertical plane.

10. In a director, a head rotatable about a Vertical axis. va. telescopemounted on said head and pivotable about a horizontal axis, the rotationof said head defining the input azimuth of the line of sight of saidtelescope with respect to the ground, and the pivoting of said telescopedefining input elevation of the line of Sight of said telescope withrespect to the ground, a cradle mounted on said director rotatable abouta horizontal axis, the rotation of said cradle defining output azimiithof the line of sight of said telescope with respect to a Vertical planeperpendicular to the ground, a slide supported on said cradle forhorizontal reciprocation with respect thereto, the posi-l tion of saidslide defining output elevation of the line of Sight of said telescopewith respect to said Vertical plane, linkage means connecting saidrotating head and said cradle for transferring the rotation of said headto said cradle, there being a connection between said telescope and saidlinkage and between said linkage and said slide for transferring thepivoting of said telescope to said slide.

ll. Apparatus for tracking the present position of a moving target inspace comprising, a director having a head rotatable about a Verticalaxis, a telescope mounted on said head and pivotable about a horizontalaxis, the rotation of said head and the pivoting of said telescopedefining azimuth and elevation of the line of sight of said telescopewith respect to the ground, and mechanical linkage means integrallyrotatable with said head and movable in response to the pivoting of saidtelescope for converting said azimuth and elevation of the line of sightof said telescope to azimuth and elevation referred to a Vertical planeperpendicular to the ground.

12. The apparatus in claim ll with cradle means rotatable about ahorizontal axis, and including means horizontally slidable mounted onsaid rotatable cradle, said rotatable cradle defining azimuth withrespect to said Vertical plane, and said slidable means definingelevation with respect to said Vertical plane, and swivel meansconnecting said linkage with said rotatable cradle and said slide.

13. The apparatus in claim 12 wherein said rotatable cradle comprises apair of horizontally spaced Vertically upstanding brackets mounted onsaid director, each said bracket having horizontally directed holes forreceiving opposed stud shafts, said cradle being mounted for horizontalrotation on said stud shafts 'and between said brackets.

14. The combination in claim 13 including a pair of spaced horizontalbars forming a part of said cradle and defining a guide track for saidslide, a bell crank member having its apex received in said track andpivotally mounted on said horizontal bars, said bell crank member havingone leg swivelly connected to said linkage and the other leg with itsfree end abutting a Vertical face on said slide member.

15. An apparatus for tracking the present position of a moving target inspace comprising, a plate rotatable about a Vertical axis, a telescopemounted on supports secured to the top surface o said plate andpivotable about an axis parallel to said plate, means driven by thepivotable movement of said telescope for transmitting elevation withrespect to the ground of a target in the line of sight of said telescopeto a gun mount, second means driven by the rotation of said plate fortransmitting azimuth with respect to the ground of a target in the lineof sight of said telescope, a cradle mounted on said apparatus androtatable about an axis parallel to the ground, a gear mounted on saidcradle axis unitarily rotatable therewith, third means driven by saidgear for transmitting azimuth with respect to a Vertical planepcrpendicular -to the ground of a target in the line of sight of saidtelescope, a slide mounted on said cradle rotatable therewith andhorizontally reciprocable with respect thereto, fourth means driven bysaid slide for transmitting elevation with respect to said Verticalplane of a target in the line of sight of said telescope, and axisconverter linkage connecting said telescope and said plate with saidcradle and said slide whereby movement of said telescope to obtainelevation and azimuth witli respect to ground of a target in the line ofsight of said telescope is converted to azimuth and elevation wtihrespect to said Vertical plane.

Lovell et al. Sept. 24, 1946 Gerks June 3, 1952

